package Demo03.Map;

import java.util.HashMap;
import java.util.Hashtable;

public class Demo02Hashtable {
    public static void main(String[] args) {
        HashMap<String,String> map = new HashMap<>();
        map.put(null,"a");
        map.put("b",null);
        map.put(null,null);
        System.out.println(map);

        Hashtable<String,String> table = new Hashtable<>();//Hashtable不能存放null，否则会异常
    }
}
